Update Document to Create List Attachment

I have a list workflow which takes data from a form and fills in controls in a MS-Word template using Update Document. It should then save the filled-in template as an attachment to the list item, either creating a new attachment file, or overwriting the old attachment file. The next step would be to convert the attached Word file into a PDF using Convert Document, also attaching the PDF to the list item. The PDF would be created if new, or would version up if existing (this is run repeatedly as the list item is updated.

If it would help, I could put the word and, if necessary, PDF into a document library (Shared Documents, same folder as Update Document's source URL), but I would still need to copy/attach the PDF to the list item.